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Home >> GMC >> 2003 >> Safari Van Cargo, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 81 (Engine Controls - Self-Diagnostics - 4.8L, 5.3L & 6.0L) >> Diagnostic Tests >> DTC P0141 & P0161: Ho2S Heater Circuit - Bank 1 & 2, Sensors 2 (6.0L W/Case Ground) >> Diagnostic Procedures

Diagnostic Procedures

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  1. Did you perform the Diagnostic System Check-Engine Controls? If yes, go to next step. If no, see DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM.
    2. NOTE: Allow the engine to cool for about one-half hour before proceeding with this diagnosis.
  2. Turn OFF the ignition. Install the scan tool. Turn ON the ignition, with the engine OFF. Monitor the HO2S signal voltage on the scan tool for 2 minutes. Does the HO2S voltage go from a bias voltage to more than or less than 300-600 mV? If yes, see DIAGNOSTIC AIDS . If no, go to next step.
  3. Inspect the HO2S fuse for an open. Is the HO2S fuse open? If yes, go to step  11. If no, go to next step.
  4. Raise the vehicle. Disconnect the HO2S electrical connector. Probe the ignition 1 voltage circuit at the PCM side of the HO2S electrical connector using a test lamp connected to a known-good ground. Do not use the HO2S heater ground or the HO2S low signal circuits. Does the test lamp illuminate? If yes, go to next step. If no, go to step  7.
  5. Connect the test lamp between the HO2S ignition 1 voltage and the HO2S heater ground. Does the test lamp illuminate? If yes, go to next step. If no, go to step  8.
  6. Use a Digital Multimeter (DMM) in order to measure the resistance between the HO2S ignition 1 voltage and the HO2S heater ground at the HO2S pigtail. Is the resistance 3.5-14.0 ohms? If yes, go to step  9. If no, go to step  10.
  7. Repair the open in the HO2S ignition 1 voltage circuit to the HO2S. After repairs, go to step  12.
  8. Repair the open in the HO2S heater ground circuit. After repairs, go to step  12.
  9. Test for a poor connection at the HO2S harness terminals. If you find a poor connection, repair the terminal as necessary. Did you find and correct the condition? If yes, go to step  12. If no, go to next step.
  10. Replace the affected HO2S. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. After repairs, go to step  12.
  11. Locate and repair the short to ground in the HO2S ignition positive voltage circuit. Replace the faulty fuse. After repairs, go to next step.
  12. Clear the DTCs with a scan tool. Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running DTC. Does the DTC run and pass? If yes, go to next step. If no, go to step  2.
  13. Observe the stored information, Capture Info with a scan tool. Does the scan tool display any DTCs that you have not diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay.
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